Applying treads to tire casings



March 26, 1929. P. w. LEHMAN APPLYING TREADS TO TIRE CASINGS Filed Oct. 9, 1926 Paul W Lehm an Patented- Mar. 26, 1929 UNITED 'sT-A res PATENToFFICE.

PAUL w. LEHMAN, or MILWAUKEE, wrsconsin, ASSIGNQB. TO THE FISK RUBBER COMPANY, OF CHICOPEE FALLS, MASSACHUSETTS, A CORPORATION OF MASSACHU SETTS.

APPLYING. TZRiEADS TO CASINGS.

1 Application filed Qetolier 9, 192s. seriarn 140,569.

My invention relates to a method ofapplying the tread rubber to'the carcassofpneumatic tire casings anda device which v may be used for carrying out that method. The tread rubber is usually formedvas a strip,of desired cross section, either by the use of a suitably shaped tubing die or grooved calender rolls. V

The tread rubber is usually f formed as a strip of desired cross section either by the use of a suitably shaped tubing die er a cal-- ender having suitably grooved rolls. It has been the practice heretofore to cut this strip into lengths substantially equal to the outer circumference ofthe tire casing. For economy of operation it is the usual practlce to cut the tread strip into lengths'as it comes from the forming means, a cooling tank being interposed between'the cutter and the forming means. The cooling operation'is necessary, among other reasons, becausethe stock has a. tendency to shrink as it cools. Valuation 1n the amount of shrinkage wh ch has taken place at the time the tread is cut," with a consequent variation 1n the amount of shrinkage of the treads afterthey are cut to length, has theresult that atv the time f the tread-s are finally applied to thetire 'car- 'cass they vary in lengthy and this variation has proved a troublesome factor in the machine application of the treads to the carcass.

In practically all of the devices now in use for the purpose the treadiis held stretched to exact length around a drum or on a flat surface and applied directly from such drum orsurface to thecarcass. Such devices are cumbersome and require an extra handling Y of the tread in placing it on the drum or surface. Furthermore the volume of tread going into different tires var es due to vary 111g degrees of shrinkage at the time the tread is cut to length. n r a c 7 It is the object of my invention to proto the tire carcass.

Other and further objects will be ap'p'arent from the follo claims. I

In the accompanying drawings wh ch-i1;

wing specification and lustrate one embodiment of my invention Figurel is "a side elevationof my device in operative relation to the building core,

ture as shown in Figure 1 with the core omitted, 1 H I p igure 4 is a fragmentary plan view show-' ing the device in inoperative position,

Figure 5 is a detailof the pressure adj usting means, an'd" Figures 6 and 7 are details showing the looking cans in unlocked and locked positions respectively. v

I believe that the so called shrinkage of the. tread is, in substantial part a longitudinal contraction due tothe fact that in passing through the hot 'die' of the tuber or the heated calender rolls the rubber is ex pandedand drawn out longitudinally causing an interior stress which when the-tread strip'is relieved from pressureand allowed cross section after it has been allowed to completely cool and shrink thanat the time it left the calender, and this volume and weight progressively increases from the time 1t leaves the calender. until cooling and ing and cooling process and later stretched to normal length about a drum or on a flat surfacefrom which it maybe directly transrubber in thetreads will vary depending on the timeat which they werecut to length.

- According tomy method I propose to cut shrinkage is complete. The strip may be. i i i cut to length at any time during the shrinkferred to the'tire carcass and the ends will meet, but itis obvious that the volume or the tread to exact Weight ratherthan to exlength andapply. the tread to the casing under a predetermined degree of tension or stretch so as to bring the tread to the desired per foot'volume and length required to havetheends meet when applied to the carcass result in a uniform volume of tread. .While my method can be carried out by the applying devieesnow in use, I prefer to use a dev-iee embodying'the principles disclosed in the accompanying drawings which takes advantage of theunif orm volume or weight .of the tread to accomplish a substantial simplifieation of; the applying device.

, Referring to the drawin s ldesignates the {rotatable core of a tire uilding maehine,

upon which the tire carcass is formed and which .ervcs as a support for the latter while the tread is applied. The applying device comprises a presser roll 2 rotatably mounted on a stub shaft 3 carried by a frame 4 pivotally secured'to a bracket {3 suitably sccurof to or formed integral with, the frame of the building machine. Frame 4 comprises an upright 7 connected. by cross members 8 and 9 to a tubular member 10 rotatably mounted on an upright shaft 11, between fixed collars 12 and 18. Shaft 11 is adjustably secured to bracket 6 as shown in Figure 5. As shown in the latter figure the end of shaft 11 which is threaded passes through a slot 14 formed in bracket 6 and the shaft is clamped in adjusted position by a nut 15. Thisadjustment of shaft 11, as is obvious controls the distance of roll 2 from the core when the device is in operative position as shown in Figure 1, and consequently the pressure applied to the tread 16 as the latter is pressed against the core as shown in dotted lines in the latter figure. In order to secure a line adjustment of the position of shaft 11, the collar 13, is provided with a threaded extension 17 passing through a lug 18 secured to bracket 6 and provided with nuts 19 and20,. lVith nut 15 loosened nuts 19 and 20may be manipulated in an obvious manner to adjust the position of shaft 1.1 after which nut 15 is tightened to firmly hold the shaft in adjusted position,

I also provide means for locking the device inoperative position as shown in Figures 1 and 2. As best shown in Figures 3, (3 and '7 this means comprises a vertical shaft 21, journaled' in lugs 22 and 23 secured to cross members 8 and 9, and provided at its lower end with a locking cam 24. The up per end of shaft 21 is bent shown in Fig ure 3 to form a handle. Collar 13 is provided with an arm 25 carrying a pin 26 adapted to cooperate with cam 24. When the device is swung from the inoperative position shown in Figure 4 to tl ie'operative Josition shown in Fi ure 2 cam 24 as shown in Figures 4 and 6 is in a position to pass pin 26 and is thereafter turned as shown in Figure 7 to engage pin 26 to force the roll 2 firmly against the tread and lock it in such position.

As shown in Figures 1 and 2 frame 4 includes rearwardly extending members 28 and 29, supporting a curved tread guide men: er 30 and tread supportingrollers 31, 32 and 33.

In operation the roll 2 is swung into posi-' tion adjacent the core, the tread to be applied is laid; on guide member and rollers 31, 32 and 33 and the forward endbrought around roll 2 and pressed against thelcore by the action of locking cam 24 against pin 26. The core is then set in rotation, thereby drawing the tread onto the tire, the operator keeping the tread snugly against roll 2 and centered in guide 80 and the groove of roll 2. If the tread has contracted to increase its volume and consequently its thickness the pressure of roll 2 transversely compresses the tread thereby stretching it longitudinally in the direction of its free end with the result that as it is applied it is brought to the predetermined cross section and length and the ends of the tread are broughtinto desired relation on completion of the rotation of the core. In other words a given volume of tread rubber is brought to proper length as it is applied to the carcass by the application of pressure, if shrinkage has taken place.

I claim:

1. A device for applying the tread to a tire carcass comprising a grooved roll adapted to be moved into a predetermined fixed spaced relation with respect to a rotatable core adapted to support the tire carcass, and means to lock the roll against movement away from the core.

roll and core, and means to lock the roll against movement away from the core.

4. A device for applying the tread to atire carcass comprising a grooved roll adapted to be moved into a predetermined fixed spaced relation with respect to a rotatable core adapted to support the tire carcass, and means to lock the roll against movement away from the core, means to freely support a tread strip adjacent the roll andm'eans to guide the strip from the support to the roll. 1

5 A device for applying the tread to a tire carcass comprising a freely rotatable grooved roll adapted to be moved into a predetermined fixed spaced relation with re spect to a rotatable core adapted to support the tire carcass, and means to lock theroll against movement away from the core, means to freely support a tread strip adjacent, the roll and means to guide the strip from the support to the roll.

6. A device for applying the tread to a tire carcass comprising a grooved roll adapted to be moved into a predetermined fixed spaced relation with respect to a. rotatable core adapted to support the the carcass,

roll and core, and means to lock the roll against movement away from the core, means to freely support a tread strip ild'jitcent the roll and means to guide the strip from the support to the roll. I

7. A device for applying the treadto a tire carcass comprising a roll provided with a groove corresponding substantially to the with respect to a rotatable core adapted to I support'the tire carcass, means for adjusting the fixed spacing of the roll and core, and means to lock the roll agalnst movement 7 away from-the, c0re, mean's to freely support v a a tread strip adjacent, the roll and means to guide the strip from the support to the roll.

In testimony whereof I have signed my name to the above specification. tread cross section and adapted to be moved 7 v into a predetermined fixed spaced relation PAU 7W. LEHMAN. 

